The present invention relates to mixing apparatus which mix audio signals, and computer programs for the mixing apparatus.
As well known, audio mixers are mixing apparatus which include a predetermined plurality of mixing buses and which mix a plurality of audio signals, via the mixing buses, at desired tone volume levels. Digital mixers are mixing apparatus which perform mixing processing and other necessary processing, such as effect impartment, through digital signal processing. In such digital mixers, audio signals, such as tone signals and digital audio signals, input via a plurality of input ports, are allocated and supplied to desired one or ones of a plurality of input channels. Each of the input channels adjusts characteristics and level of the signal allocated thereto and then supplies the thus adjusted signal to desired mixing buses. Each of the mixing buses mixes a plurality of the digital signals supplied from the input channels and supplies the resultant mixed signals to corresponding output channels. Each of the output channels adjusts characteristics and level of the supplied signal and then outputs the thus-adjusted signal to the outside of the mixer. Among examples of digital mixers of the above-discussed type is a digital mixer marketed by the assignee of the instant application under the product name “PM1D” (see, for example, http://www.2.yamaha.co.jp/manual/pdf/pa/japan/mixers/PM1D_ManagerJ.pdf).
In this specification, allocating signals of input ports to input channels or allocating output signals of output channels to output ports will be referred to as “patch” or “patching”, and setting data of such patching will be referred to as “patch data”. Allocation (or patching) of the signals from the input ports to the input channels is performed by an “input patch” section, while allocation (or patching) of the signals from the output channels to the output ports is performed by an “output patch” section.
Generally, the digital mixers, such as the one marketed under the product name “PM1D” mentioned above, are provided with a plurality of input ports including analog input ports each for inputting an analog audio signal and digital input ports each for inputting a digital audio signal.
The analog input port is provided with a gain-variable amplifier and A/D converter. Analog audio signal input to the analog input port is appropriately adjusted in amplitude level by the gain-variable amplifier and then converted via the A/D converter into a digital audio signal. Then, the thus-converted digital audio signal is supplied via the input patch section to one or more input channels that are patched-to destinations of the analog input port (i.e., “patched-to input channels”). Further, the digital input port, which may comprise a digital audio I/O based on the AES/EBU, ADAT, TDIF or other standard or an audio network I/O like the Cobranet (trademark) or mLAN (trademark), is capable of inputting a plurality of digital audio signals by means of a single cable.
Via a gain control mechanism provided in the analog input port, the user is allowed to adjust the input analog audio signal to an optimal gain level that can reliably prevent the A/D-converted digital signal from assuming too small a level and prevent signal clipping from occurring due to an excessive input to the A/D converter or excessive gain of the A/D converter. However, if the gain of the analog input port is adjusted, signals to be processed in input channels that are patched-to destinations of (i.e., patched-to input channels connected to) the analog input port, namely, signals that are supplied via the patched-to input channels to the mixing buses, would vary in level, which thereby undesirably influences a mixing level ratio among the signals.
At an input stage of each of the input channels, there is provided a level control mechanism called “attenuator” which attenuates or amplifies the level of the audio signal input to the channel in question. This attenuator is provided to appropriately adjust the level of the audio signal, input to the channel, with effects of an equalizer etc., provided at subsequent stages, taken into consideration.
When gain adjustment has been performed in the analog input port and if the attenuator of a given patched-to input channel connected with the analog input port is adjusted to cancel out level variation having occurred due to the gain adjustment, the signal mixing ratio can be prevented from changing. However, the conventionally-known mixing apparatus are not constructed with interlocked relation between the gain adjustment of the input ports and the adjustment of the attenuators of the input channels taken into consideration; to date, it has been conventional to perform such adjustment through manual operation by users. Speaking of possible arrangements for interlocking the gain adjustment of a given input port and the adjustment of the attenuator of a corresponding patched-to input channel to each other, the input ports and the input channels may be connected with each other in desired combinations and any of the input ports may be connected to two or more patched-to input channels. However, that the gain of a given input port is adjusted in accordance with adjustment of the attenuator of a given patched-to input channel is practically unreasonable in view of the intended purpose of the attenuator. Therefore, the arrangements for merely interlocking the gain adjustment of a given input port and the adjustment of the attenuator of a corresponding input channel to each other alone are not sufficient.